Motoscrubs.com

I intend to lace new rims to the standard hubs. Rims WM1 18" as original fitting.

I cut through all the rear spokes before thinking to keep one intact. On the front, I did keep one.

The front measures 188mm centre of bend to end and 175 to thread. The Mototrans parts book (thank you www.lamaneta.com) has it listed as 152mm and the rear 6mm longer at 158mm although the scan resolution is poor. Inner and outer spokes are the same length as each other.

Anyone know the rear spoke length bend to end or bend to thread please?

The spoke lengths on many of the Mototrans machines are often similar to the Italian models.
The 175, 200 and some 250 models are almost identical.
You quote a rear spoke length of 158mm, which seems correct.
Measuring a rear spoke, I find the length from bend to thread to be about 140mm, which allowing for a spoke nipple length of 18mm would seem correct.
However, your front spoke length seems to be very long.
The Mototrans parts book states 152mm and an Italian parts book states 151mm, whereas you say yours is 188mm.
Have you got the correct size 18 inch rim, or an Italian 160 hub, as 188mm is very long?
Post a picture of your bike and it may become clearer.

Jon

Jon, thks. Pics >

I see the reason for your extra long spokes from the photo of your front wheel.
These wheels are normally spoked 'over two', which means that each spoke passes over two spokes on the same side.
Your wheel has been spoked 'over three', with each spoke crossing three spokes on each side.
I would suggest that you fit spokes of the original length and revert to the 'over two' form on your front wheel.
That is assuming that the rim has not been drilled over-thin where the spoke nipples fit, in which case a replacement rim is required.

Jon

You are absolutely right!

Never thought to check - assumed they were originals. New rims came with the bike.

Makes sense of why I found the outer spokes were bent across the hub bevel!

I will go with the Mototrans spec lengths - thanks for the measured and Italian confirmation.

The spoke drillings look to be at a lesser angle on the new rims and better positioned?

Task now to find supplier with correct spoke end proportions and angles. Pics >

Central Wheels made my spokes. You can either send old ones in as patterns, or fill in their spec. sheet.
Ian

Ranton, thanks for that: I'll keep them in mind.

Jon,

I've acquired a set of spokes of correct length. They all work out if the inner ones of both sides are fitted in the same direction. If they are fitted in the opposite direction then they are too short. The picture shows this. All nipples are only on a couple of turns - the discrepancy would increase with tightening.



The hole at the top of the upper flange has an inner spoke fitted. The lower flange has all inner spokes fitted. The rim is conventionally drilled.

One spoke of opposite direction is inserted to show the discrepancy in length.

It would seem that the wheels were originally built using all inner spokes in the same direction as each other and all outer spokes in the opposite direction to the inners. I have laced one that way and it works out. Looking at restorations online (Sammy Miller, Bonhams, etc) show the more conventional LH & RH inners in opposite directions and LH & RH outers in opposite directions.

The countersinks in the hub flanges dictate where inner and outer spokes fit. There are no other alternatives to the two above. I would be very interested to know what lacing others have that use the parts catalogue spoke lengths and what spoke lengths work out for the conventional lacing.